[OpenWrt-Devel] [PATCH v2 1/2] ramips: second spi device on rt5350

[jonsmirl at gmail.com]

This site has a write up on how SPI mode works.
http://elm-chan.org/docs/mmc/mmc_e.html




On Tue, Aug 19, 2014 at 3:59 PM, jonsmirl at gmail.com <jonsmirl at gmail.com>
wrote:

>
>
>
> On Tue, Aug 19, 2014 at 3:48 PM, Álvaro Fernández Rojas <noltari at gmail.com
> > wrote:
>
>> El 19/08/2014 21:43, jonsmirl at gmail.com escribió:
>> > How is the clock speed wrong?
>>
>> The lowest speed the RT5350 SPI controller can achieve is System Clock /
>> 128.
>> System Clock = 120MHz
>> Lowest SPI Clock = 120MHz / 128 = 937.5KHz
>>
>> However, the MMC/SD cards need to be initialized at 100-400KHz.
>>
>
> This might work... Put the SPI pins into GPIO mode. Use the kernel
> bit-bang support for SPI to initialize the card.  Then go back to high
> speed mode.
>
> --
> Jon Smirl
> jonsmirl at gmail.com
>



-- 
Jon Smirl
jonsmirl at gmail.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.infradead.org/pipermail/openwrt-devel/attachments/20140819/51c068ea/attachment.htm>
-------------- next part --------------
_______________________________________________
openwrt-devel mailing list
openwrt-devel at lists.openwrt.org
https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel